# -*- coding: utf-8 -*-

# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.html

from scrapy import signals
import redis
from scrapy.exceptions import IgnoreRequest


class NewsSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Response, dict
        # or Item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class NewsDownloaderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class Save404URLDownloaderMiddleware(object):
    # 保存404网址到redis，避免重复访问
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    def __init__(self, redis_host, redis_port, redis_password, redis_key):
        self.redis_host = redis_host
        self.redis_port = redis_port
        self.redis_password = redis_password
        self.redis_key = redis_key
        self.client = None

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls(
            redis_host=crawler.settings.get('REDIS_HOST'),
            redis_port=crawler.settings.get('REDIS_PORT'),
            redis_password=crawler.settings.get('REDIS_PASSWORD'),
            redis_key=crawler.settings.get('REDIS_KEY'),
        )
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def spider_opened(self, spider):
        self.client = redis.Redis(host=self.redis_host)

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.
        if response.status == 404 or response.status == 403:
            self.client.sadd(self.redis_key, response.url)
            print("save 404url to redis, url: ", response.url)
        return response

        #if response.status == 110 or response.status == 111:




class DropExistURLDownloaderMiddleware(object):
    # 丢弃掉已存在redis news集合中的url的request

    def __init__(self, redis_host, redis_port, redis_password, redis_key):
        self.redis_host = redis_host
        self.redis_port = redis_port
        self.redis_password = redis_password
        self.redis_key = redis_key
        self.client = None

    @classmethod
    def from_crawler(cls, crawler):
        o = cls(
            redis_host=crawler.settings.get('REDIS_HOST'),
            redis_port=crawler.settings.get('REDIS_PORT'),
            redis_password=crawler.settings.get('REDIS_PASSWORD'),
            redis_key=crawler.settings.get('REDIS_KEY'),
        )
        crawler.signals.connect(o.spider_opened, signal=signals.spider_opened)
        return o

    def spider_opened(self, spider):
        self.client = redis.Redis(host=self.redis_host)

    def process_request(self, request, spider):
        if self.client.sismember(self.redis_key, request.url):
            # print("url已经爬过，该request将被略过。url: "+request.url)
            raise IgnoreRequest
        else:
            request.headers['Referer'] = None
            return None
